Known sealing washers generally comprise a ring of rubber-like material molded or otherwise secured within a metal washer but are not suitable for high pressure applications in connection with socket head cap screws and the like which have narrow annular shoulders defined between the heads and shanks thereof. The clamping shoulders of socket head cap screws are generally of narrow radial width, for example 1/16" on 1/4" diameter cap screws, 1/8" on 3/4" diameter cap screws, 1/4" on 11/2" diameter cap screws, etc. whereby in high load and pressure installations using, for example, SAE grade 5 or grade 8 cap screws, the metal portion of the sealing washer must be of relatively thick stock to withstand high compression loading, and the sealing portion must be of relatively narrow radial width but yet must be retained against extrusion under high fluid pressure.
Sealing washers of the types disclosed in U.S. Pat. Nos. 2,795,444 and 3,170,701 are adapted to be used only with a fastener having a head of considerably larger diameter than the shank thereof because the sealing ring thereof has an outer portion anchored in openings through the inner portion of the retainer and hence the head of the fastener must extend radially beyond the anchor openings to apply clamping pressure on the retainer and to prevent extrusion of the sealing ring under high fluid pressure. Moreover, in these sealing washers the retainers must be made of relatively thick stock to provide for anchoring of the sealing rings thereto and for resisting cupping under high clamping pressures.